Separable heat pipe assembly

ABSTRACT

A separable heat pipe assembly for stabilizing the generally frozen soil adjacent and supporting a structural member or foundation in permafrost or similar regions, including a cooperative combination of a sheath installed in the frozen soil and a closely mating heat pipe element normally inserted into the sheath with a substance of good thermal conductivity filling the small void remaining therebetween. The underground sheath preferably has a plurality of heat gathering fins and the mated heat pipe element preferably has an integral radiator section protruding aboveground. The thermal substance is preferably a liquid mixture of water and ethylene glycol, for example, mixed in a selected ratio.

Anderson et a1.

- [[11] 3,823,769 [451 July 16,1974

SEPARABLE HEAT PIPE ASSEMBLY Inventors: John H. Anderson; Elmer D.

Waters, both of Richland, Wash.

Assignee: McDonnell Douglas Corporation, Santa Monica, Calif.

Filed: Nov. 2, 1972 Appl. No.: 303,221

US. Cl 165/76, 165/45, 165/104,

165/105, 165/185 Int. Cl. F28d 15/00 Field of Search 165/45, 105, 76, 104, 185,

References Cited UNITED STATES PATENTS FOREIGN PATENTS OR APPLICATIONS 938,372 10/1963 Great Britain 165/164 Primary Examiner-Albert W. Davis, Jr. Attorney, Agent, or Firm-D. N. Jeu; Walter J. Jason; Donald L. Royer 5 7 ABSTRACT A separable heat pipe assembly for stabilizing the gencrally frozen soil adjacent and supporting a structural member or foundation in permafrost or similar regions, including a cooperative combination of a sheath installed in the frozen soil and a closely mating heat pipe element normally inserted into the sheath with a substance of good thermal conductivity filling the small void remaining therebetween. The underground sheath preferably has a plurality of heat gathering fins and the mated heat pipe element preferably has an integral radiator section protruding aboveground. The thermal substance is preferably a liquid mixture of water and'ethylene glycol, for example, mixed in a selected ratio.

10 Claims, 8 Drawing Figures I SEPAR-ABLE HEAT PIPE ASSEMBLY BACKGROUND OF THE INVENTION Our invention relates generally to support structures and, more particularly, to a novel and useful-heat pipe assembly for use with support structures or foundations in permafrost areas or in any areas having active ground layers subject to a severe annual freeze-thaw cycle.

Permafrost is material which is largely frozen permanently. It is usually a mixture of soil, rock and ice although it can be anything from solid rock to muddy ice. In the arctic regions, permafrost may extend from a few feet to hundreds of feet below the surface. The permafrost is separated from the surface by an upper soil layer commonly called the tundra which supports a dense growth of surface vegetation. The tundra is subject to a seasonal freeze-thaw cycle and serves as insulation to limit permafrost thaw in the summer. The thaw in the summer, however, can create an unstable condition for structures constructed in the arctic regions. This is, of course, more so in wet, ice-rich, permafrost areas than in dry, stable, permafrostv areas of well drained soil or rock.

There are severe problems associated with support man and his machines. When the tundra is broken or removed, the permafrost loses its insulation and begins to melt and erode. Thus, tracks left by a tractor or caterpillar train can become a deep ditch and alter the surface drainage pattern over-a wide area.

In cities and regions which overlay permafrost areas, a gravel insulating technique is generally used in construction over such areas. A raised gravel pad, for example, is ordinarily employed to provide a suitable support or work area on permafrost. Foundation structures embedded in permafrost are also commonly ,surrounded completely by a layer of insulating gravel. In areas of ice-rich permafrost and/or during a strong summer thaw, however, even the use of a relatively some subsidence and possibly accompanying damage of the supported structure or apparatusfOn the other hand, instead of subsiding, support posts or poles for arctic overhead communications and power lines have presented a particular problem with pole jacking wherein the annual seasonal uplift due to frost leave can actually lift the poles and their anchors completely out of the ground. The pole jacking problem has plagued all of the utility companies throughout vast areas of the arctic and subarctic regions.

The patent application Ser. No. 174,687 of Elmer D; Waters on Permafrost Structural Support With Heat Pipe Stabilization filed Aug. 25, 1971 discloses and claims a cooperative combination of a support structure and heat pipe element installed in generally frozen soil. The heat pipe element is of a suitablycomplementary configuration and/or disposition with respect to the support'structure to provide appropriate stabilization of the surrounding frozen soil. In one embodiment, the heat pipe element is disposed externally of the sup-' posed internally of (and integrally combined with) such structure. The external embodiment further includes one version employing'a linear (straight) heat pipe element and another version employing an angular (helical) element. In both versions of the external embodiment, an overlapping joint can be provided to join an aboveground radiator section of the heat pipe element to an underground embedded section thereof. This permits the upper radiator section to be readily separated and detached from the lower embedded section at the joint.

' The heat pipe element just described above and various other natural convection heat transfer devices used for stabilization of permafrost foundation areas present a problem when complete device replacement is necessary, even if the device is not part of the support structure. Replacement usually requires the digging of a new hole and this maybedifficult to accomplish in remote and rugged regions where a drilling rig cannot be easily transported and/or used; In addition, if the particular installation first requires removal of the old device, this SUMMARY OF THE INVENTION Briefly, and in general terms, our invention is preferably accomplished by-providing a separable heat pipe assembly for stabilizing the normally frozen soil adjacent and supporting, for example, a structural member or foundation used in arctic, subarctic or similar regions, including a cooperative-combination of a heat gathering sheath which is normally installed in the generally frozen soil and a closely mating heat pipe element which is normally inserted into the sheath with a substance of good thermal conductivity generally filling the small void therebetween. The sheath is normally embedded fully underground either adjacent to the structural member or within the foundation bed, and I preferably has longitudinal fins which are circumferentially spaced from each other and extend radially from the sheath.

The heat pipe element broadly includes an elongated tubular container having a filling or charge of a suitable working fluid, a wick or condensate spreader element in the container and a heat exchanger (radiator) suitably coupled or integrally incorporated with an upper portion of the tubular container. The-lower portion of the tubular container can be inserted into the embedded'sheath with the upper portion (and its radiator section) protruding aboveground. The bottom of the tubular container normally rests against the inside bottom of the sheath, leaving a generally annular space between the sides thereof. Heat transfer between the sheath and lower portion of the heat pipe element is facilitated by filling the small annular space with an appropriate thermal substance which is preferably a liquid mixturev of water (H 0) and ethylene glycol (HOCHg'CHgOII), for example.

The average or nominal thickness of the annularspace between the sheath and heat pipe element is an important feature of this invention. It must be large n enough to permit relatively easy insertion of the lower portion of the. heat pipe element into the sheath and similarly easy subsequent withdrawal if desired or necessary. It must, however, be kept as small as is conveniently possible since most substances which could be used to fill the annular space would normally have a thermal conductivity less than that of the sheath and heat pipe element (metallic) materials,'and minimizing the thickness of the annular space will tend to minimize the thermal losses and lead to higher performance.

The selection of the substance to fill the annular space between the sheath and heat pipe element is ordinarily based upon the desire to obtain as good a thermal conductivity therebetween as possible consistent with the existing constraints. Ice has relatively good thermal conductivity and, therefore, water can be conveniently used in a variety of applications of the invention. A water and ethylene glycol mixture of various proportions or ratios may be preferably used. A small amount, such as 3%, of ethylene glycol will lower the freezing point a few degrees and may be necessary in certain instances where the use of water only would lead to prompt ice formation in'the sheath and, thus,

prevent insertion of the closely mated heat pipe element.

Different ratios of the water and ethylene glycol mixture can be chosen. It may be desired or required, for example, to lower the freezing point of the mixture such that it would rarely, if ever, freeze so that the heat pipe element can always be easily removed and replaced. A penalty in thermal performance-would be involved since any water and ethylene glycol mixture has a poorer thermal conductivity than ice (water only); however, the penalty may be acceptable in orderto ob.- tain other desired characteristics. Of course, a wide variety of different thermal substances such as other liquids, mercury, a-paste or, in their absence, even air (with the thin annular space) can be used instead of the water and ethylene glycol mixture.

The exterior shape of the sheath can be designed according to its usage and nature of the surrounding soil or other factors. It can be round, square or irregular, finned or unfinned and, if finned, with any selected number of fins of different arrangement and geometry. The fins on the sheath, or on the radiator section of the upper portion of the heat pipe element, can be laterally or longitudinally arranged and of uniform or varying widths and thicknesses, for example. The interior shape of the sheath can be cylindrical with a hollow circular crosssection to mate with a complementary exterior shape of the lower portion of the heat pipe element and is usually most convenient. Of course, the complementary shapes of the sheath and corresponding portion of the heat pipe element can have other cross sectional configurations such as oval, rectangular, triangular, etc., which can be constant or diminishing in area with length from top to bottom, for example.

BRIEF DESCRIPTION OF THE DRAWINGS Our invention will be morefully understood, and other advantages and features thereof will become apparent, from the following description of certain exemplary embodiments of the invention. The description is to be taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a fragmentary elevational view of a structural support assembly installed in generally frozen soil,

4 including a cooperative combination of a support structure and a separable heat pipe assembly according to this invention;

FIG. 2 is a cross sectional view of the structural support assembly as taken along the line 2--2 indicated in FIG. 1;

FIG. 3 is a fragmentary elevational view, shown partially broken away in section,of the heat pipe element of the separable heat pipe assembly;

FIG. 4 is a fragmentary elevational view, shown partially broken away in section, of the sheath of the separable heat pipe assembly;

FIG. 5 is a cross sectional view of the separable heat pipe assembly as taken along a line through the lower portion thereof, with the heat pipe element installed in its sheath;

FIG. 6 is a fragmentary elevational view of another version of a heat pipe element of a separable heat pipe assembly;

FIG. 7 is a fragmentary elevational view of another version of a sheath, installed in a foundation bed, for the heat pipe elementof FIG. 6; and

FIG. 8 is a cross sectional view of the sheath, with its heat pipe element installed therein, as taken along the line 8-8 indicated in FIG. 7. DESCRIPTION OF THE PRESENT EMBODIMENTS In the following description and accompanying drawings of certain illustrative embodiments of our invention, some specific dimensions and types of materials are disclosed. It isto be understood, of course, that such dimensions and types of materials are given as examples only and are not intended to limit the scope of this invention in any manner.

FIG. 1 is afragmentary elevational view of a structural support assembly 20 installed in generally frozen soil 22. The support assembly 20 broadly includes the cooperative combination of a support structure 24 and a separable heat pipe assembly 26. The support structure 24 is, in this instance, a utility pole; however, it can be any other form of structure such as a building pile or the like. The assembly 26 is essentially a two-piece combination of separable components including sheath S and heat pipe element y. These separable components S and y are individually shown and described later.

The utility pole 24 is regularly installed in soil 22 with the sheath'S positioned alongside the pole. The sheath.

S is preferably positioned parallel to the pole 24and directly against it as shown in FIG. 1 or as feasibly close as possible. The top 28 of the sheath S can be usually located about, for example, 1 foot below the surface of the soil 22 but it could extend above the surface. In fact, the sheath S can be an integral .(hollow) part or modified portion of the support structure as indicated in phantom lines 24a, with the heat pipe element y suitably adapted to be installed therein. The heat pipe element y broadly includes an elongated tubular container 30 having a filling or charge of a suitable working fluid such as ammonia therein, and a heat exchanger 32 suitably coupled to the upper portion of the tubular container. The heat exchanger 32 can be a passive radiator integrally incorporated with the upper portion of the container 30. The radiator 32 is formed, for example, by providing a plurality of longitudinal fins 34 which are integrally affixed to (extruded with) the upper portion of the tubular container 30 and extending radially therefrom.

The sheath S includes a central tubular body 36 for receiving the lower portion of the container 30, and a plurality of longitudinal fins 38 similar to those of the radiator 32. In inserting the lower portion of the tubular container 30 fully into the sheath S, a substance of good thermal conductivity is normally used to fill the void remaining therebetween. After proper mating of the sheath and heat pipe element components S and y, the heat pipe element can be secured in position by fastening its radiator 32 section to the adjacent section of the utility pole 24 and the components covered to the appropriate extent with soil 22. The radiator 32 is preferably given an outside white coating finish to reflect incident radiation, and the sheath S can be suitably coated on the outside to minimize soil to metal corrosion.

FIG. 2 is across sectional view of the structural support assembly 20 as taken along the line 22 indicated in FIG. 1. The radiator 32 section of the heat pipe element y is fastened to the utility pole 24 by, for example, relatively flexible sheet metal straps 40. The straps 40 are wrapped around the radiator 32 section and pole 24 near the lower and upper ends of the radiator, with the ends of the wrapped straps secured together and attached to the pole by lag screws 42. There are, of course, various other equally suitable means and methods of fastening the heat pipe element y to the utility pole 24 or other support structure.

FIG. 3 is a fragmentary elevational view, shown partially broken away in section, of the heat pipe element y. The element y includes a lower tube 44 closed by an end plug 46, an upper radiator 32 with longitudinal fins 34 and an upper pinch-off plug 48 with a cover cap 50. The lower tube 44 preferably contains a wick or condensate spreader element 52 which can be a coarse mesh wire screen or convolute element as a helical spring wire of small diameter contactingthe internal wall surface of the lower tube. The lower end of the helical wire 52 rests against the end plug 46, and the upper end extends to a point near the top 28 (FIG. 1) of sheath S when properly mated with the heat pipe element y.

The end plug 46 can be welded to the lower end of tube 44, and the upper end of the tube can also be welded in registry to the lower end 32a of the matching centraltubular body 54- of the radiator 32 which can be a fully extruded section. Pinch-off plug 48 is preferably welded to the open upper end 32b of the radiator tubular body 54 and, after charging of the heat pipe element y with a suitable working fluid such as ammonia and following pinch-off, the cover cap 50 can be welded to the pinch-off plug to protect its closed stem.

Essentially all of the parts of the heat pipe element y can be made of suitable aluminum alloy, for example. lllustratively only, the lower tube 44 can have an outside diameter of 1.050 inches and an inside diameter of 0.824 inch, and its length can typically vary from about 98 to 151 inches according to conditions and usage. Similarly, the radiator 32 can vary in length from about 60 to 120 inches with eight relatively thin fins 34 circumferentially spaced equiangularly around the radiator body 54. The longitudinal fins 34 have a diametrical spread between outer edges of, for example, 5 inches. Finally, the helical spring element 52 can be fabricated nal outside diameter of 1.100 inches and a nominal pitch of 0.50 inch. Of course, the element 52 can be omitted where the inside diameter of the lower tube 44 is small (less than, for example, approximately 0.25 inch).

FIG. 4 is a fragmentary elevational view, shown partially broken away in section, of the sheath S. Sheath S can be substantially identical to the extruded radiator 32 section of the heat pipe element y except that the central tubular body 36 of the sheath has a slightly larger inside diameter to accommodate the lower tube 44 (FIG. 3) of the heat pipe element and, additionally, has an end plug 56 welded to close the lower end of the sheath. The sheath body 36 has an inside diameter of, for example, 1.080 inches which provides with the mated lower tube 44 a generally annular space or void of 0.015 inch thickness between the side walls thereof.

The length of the sheath S can typically vary from age.

The sheath S of FIG. 4 with the end plug 56 deleted (or the sheath-can be inverted) can also represent the radiator 32 (FIG. -I) installed on the upper portion of heat pipe element y which, in this instance, can be a completely tubular container 30. A layer of thermal paste (such as Dow Corning DC-340) can, for example, be suitably applied to the upper portion of the tubular container 30 and the inner walls of the tubular body 36 of sheath S before itis installed and suitably secured on the upper portion of the tubular container.

Altemately, a thermal liquidcan be used to fill the space between the upper portion of tubular container 30 and the installed tubular body 36 of sheath S by first providing a lower seal 30a (FIG. 1) between the lower periphery of the tubular body and corresponding part of the tubular container. An upper seal 30b can be similarly provided after filling. The lower and upper seals 30a and 30b can be, for example, suitable plastic insert rings or even welds.

FIG. 5 is a cross sectional view of the separable heat pipe assembly 26 as taken along a line through the lower, mated sheath and heat pipe element components S and y, portion thereof. The sheath body 36 has a wall thickness of 0.094 inch and the longitudinal fins 38, which taper in thickness radially outwards from 0.1 10 to 0.080 inch, have a diametrical spread between outer edges of 5 inches, for example. The generally an- 1 nular space 58 between the central tubular body 36 'of from 0.060 inch diameter wire in a helix having a nomi- J sheath S and the lower tube 44 of the heat pipe element y is normally filled with a substance of good thermal conductivity. The thermal substance is preferably a liquid mixture of water and 3 percent ethylene glycol, for example. Different ratios of the water and ethylene glycol mixture, and various other thermal substances such as a paste or grease as discussed earlier can, of course, be used. A predetermined amount of liquid can be poured into the tubular body 36 of sheath S before the lower tube 44 of heat pipe element y is fully inserted therein.

The generally annular space 58 is of the order of 0.015 inch thickness for the sheath and heat pipe element components S and y having exemplary mating diameters of approximately 1 inch and lengths from about to inches. This thickness of 0.0 l 5 inch for the annular space 58'can remain about the same order even with mating diameters considerably different from approximately 1 inch since the annular space must be kept as small as conveniently possible to minimize thermal losses, and manufacturing tolerances cannot normally be made much closer to permit practical fabrication with relatively easy insertion of the lower tube 44 into (and any subsequent removal out of) the central tubular body 36 of sheath S. Thus, considering the various factors involved, a minimal thickness annular space 58 requiring little, if any, filler thermal substance is preferably provided and used in the separable heat pipe assembly 26.

Generally, while various conditions and factors must be considered, use of the separable heat pipe assembly 26 (FIG. 1) in permafrost areas typically requires a radiator 32 surface area optimumly of about 3 or 4 square feet per foot of sheath S length fully embedded in soil 22 to dissipate properly (and to a large extent by convection) the usual heat picked up by the sheath. Such radiator surface area is found to be quite sufficient with the air temperatures encountered in the per mafrost areas. Of course, on those occasions when the air temperature is unusually high, heat cannot be transferred from the air into the soil 22 by the assembly 26 because of its arrangement and the well known heat pipe mode of operation wherein gravity continually drains any condensate away from the radiator 32. The radiator 32 section can be conveniently and preferably varied in (extrusion) length to achieve any desired or necessary surface area.

Similarly, it is generally desirable to place a sheath S having the largest, relatively thin, surface area in the ground. The most economical and practical configuration for use in permafrost areas has been found to be the finned sheath S. Of course, various other sheath configurations can and have been used in different applications and/or soil conditions. More sheath S surface area is generally needed in wet soil 22 than in dry since more heat must be picked up by the heat gathering fins 38 to stabilize the surrounding soil. In the typical permafrost areas, lateral surface area provided by-the fins 38 is quite adequate for virtually all normal soil 22 conditions and it is the sheath S length which is of more importance'. The tubular container (FIG. 3) of the heat (FIG. 1) and the sheath S should be approximately of the same length except for the relatively small layer of soil 22 above the top 28 of the sheath, to ensure stabilization of a surrounding soil area which fully encompasses the underground portion of the support structure within a suitable margin.

Some commonly used lengths of the separable heat pipe assembly 26 with a nominally 1 inch diameter heat pipe are illustratively shown below. It may be noted that in certain of these examples, adequate but not optimum radiator 32 surface area is utilized because of their intended usage. All of the listed dimensions are given in inches.

Overall Length Radiator Length Sheath Length 162 60 84 I74 72 84 I80 80 80 222- 96 I08 240 I02 I20 270 I20 I20 FIG. 6 is a fragmentary elevational view of another version y of a heat pipe element for another separable heat pipe assembly. The heat pipe element y is used in applications where it is desirable to have the aboveground radiator 60 in a nearly horizontal position, such as under a building where the clearance space is too limited to accommodate a generally vertical radiator. The fins 62 of the radiator60 are preferably disposed laterally with respect to the tubular container 64 of the heat pipe element y as illustrated. The horizontal radiator 60 can provide much more surface area per unit length and, thus, the heat pipe element y is generally suited for much greater in-ground lengths than the heat pipe element y (FIGS. 1 and 3).

It is noted that the heat pipe element y of FIG. 6 can, in certain instances, be directly inserted almost horizontally into either the soil or a pocket provided in a foundation bed 66, indicated in phantom lines, where removal and replacement may be more easily accomplished than with a deep vertical hole. It is also possible to bend the tubular container 64 near or at some distance from the radiator 60 so that a corresponding portion of the tubular container can be oriented at a selected angle from horizontal. Of course, the tubular container 30 (FIG. 1) can be similarly bent at a point above the top 28 of its mated sheath S to orient the tubular container and the radiator 32 at any selected angle with respect to each other.

FIG. 7 is a fragmentary elevational view of another version S of a sheath for another separable heat pipe assembly. The sheath S is shown installed in a foundation bed 68 which can be used to support various structures (not shown). The sheath S is similar to the sheath S (FIG. 4) except that only two generally horizontally disposed longitudinal fins 70 extending radially from the central tubular body 72 of the sheath are needed or required with the relatively low foundation bed 68. The sheath S is shown illustratively inclined at a selected angle from horizontal, so that its mating heat pipe element y will be similarly inclined. A minimal slope of from 0.25 to 0.50 inch per foot is preferably provided, for example, for the sheath and heat pipe element components S and y used in the typical foundation bed 68.

It can be seen from the cross sectional view of the foundation bed 68 that its height is not great; however, its length could be quite extended as where it is the foundation bed for a railroad track or the like. In this instance, the foundation bed 68 can be constructed in regular manner coupled with the installation of spaced sheaths S which are each sealed with a cap plug 74. Thus, construction of the foundation bed 68 can proceed without obstruction by having heat pipe elements y protruding therefrom during such time. The sheath S (and sheath S of FIG. 4) can be suitably closed with a commercially available Caplug, type WW13, to keep dirt and moisture out of the sheath. When desired or necessary, the cap plug 74 can be removed from a sheath S and a mating heat therein.

FIG. 8 is a cross sectional view of the sheath S with the heat pipe element y of FIG. 6 installed therein following exposure and removal of the cap plug 74, as taken along the line8-8 indicated in FIG. 7. This separable heat pipe assembly 76 is broadly similar to the separable heat pipe assembly 26 of FIG. I. The assembly 76 has a generally annular space 78 of minimal pipe element y installed sate spreader element 80 which can be in the form of a helical spring, for example. 7

It may be noted that while the thin space 78 is not strictly annular over the full length of the mating portions, since the end of the heat pipe element y will tend to rest against a corresponding point in the sheath S to support part of the weight of the heat pipe element, a thermal substance filling the thin space would help buoy up the heat pipe element end if the substance is a liquid and would actually support it when the substance is frozen or is a solid material. Of course, it is not critical or essential that the thin space 78 be closely or nearly annular throughout the entire length of the mated portions of the sheath and heat pipe element components S and y, or that the thin space be completely filled with the thermal substance.

In another embodiment of the separable heat pipe assembly, a helical version of the sheath S of FIGS.'7 and 8 can be used. The sheath S is, in this instance, helically wrapped around the underground portion of a support structure such as the utility pole 24 shown in FIG. 1. Of course, the plane of the fins 70 is preferably wrapped helically concentric and parallel to the surface of the pole 24. The mating portion of the tubular consheath form and the tubular container 64 wholly of the 4 tube form for greater installation handling ease. It is apparent that FIG. 8 also illustrates a cross sectional view through the mating sheath and heat pipe element portions of the helical embodiment of our invention.

While certain exemplary embodiments of this invention have been described above and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of, and not restrictive on, the broad invention and that we do not desire to be limited in our invention to the specific constructions or arrangements shown and described, for various obvious modifications may occur to persons having ordinary skill in the art.

We claim:

l. A separable heat pipe assembly for installation in a permafrost environment comprising:

a sheath including a tubular body, said sheath being at least partially exposed to a heat input environment, and said tubular body being closed at one end and open at the other end;

a heat pipe element including a tubular container having a charge of working fluid therein, said tubu-' lar container comprising a first portion including a predetermined part which can be accommodated in said tubular body and mating therewith, and a second portion including a predetermined part adapted to be coupled to a heat exchanger at least partially exposed to a heat output environment,

i0 said predetermined part of said container first portion having an exterior shape complementary to the interior shape of said tubular body, and the mating portions of said tubular body and tubular container being closely spaced from each other and a first substance having a thermal conductivity greater than air generally filling the' space between the mating portions of said tubular body and tubular container, said first thermal substance including a fluid which is unsolidified at ordinary temperatures, whereby heat picked up by said sheath from said heat input environment is conducted by said first thermal substance to the mating portion of said heat pipe element and transported by said working fluid in vaporized form to said predetermined part of said container second portion coupled to said heat exchanger for transfer to said heat output environment accompanied with condensation of said vaporized working fluid for return to the mating portion :of said tubular container.

2. The invention as defined in claim 1 wherein the mating portions of said tubular body and tubular container are generally spaced in the order of about 0.015 inch from each other.

3. The invention as defined in claim 1 wherein said fluid includes a liquid mixture of water and ethylene glycol.

4. The invention as defined in claim 1 further comprising a heat exchanger including a radiator having a coupling surface positioned in proximity to said predetermined part of said container second portion, and a second substance of proper thermal conductivity generally filling thespace between said coupling surface and said predetermined part of said container second portion.

5. A separable heat pipe assembly for installation in a permafrost environment comprising:

a sheath including a tubular body, said sheath being at least partially exposed to a heat input environment;

a heat pipe element including a tubular container having a charge of working fluid therein, said tubular container comprising a first portion including a, predetermined part which can be accommodated in said tubular body and mating therewith, and a second portion including a predetermined part adapted to be coupled to a heat exchanger at least partially exposed'to a heat output environment;

a first unsolidified at ordinary temperatures substance having a thermal conductivity greater than air generally filling the space between the mating portions of said tubular body and tubular container; and

flow means for generally directing and spreading condensate flow back to said mating portion of said tubular container, said flow means including a convolute structure provided directly on a predetermined length of the interior longitudinal wall of said tubular container to spread and maintain the condensate flow thereover, whereby heat picked up by said sheath from said heat input environment is conducted by said first thermal substance to the mating portion of said heat pipe element and transported by said working fluid in vaporized form to said predetermined part of said container second portion coupled to said heat exchanger for transfer to said heat output environment accompanied with condensation of said vaporized working fluid for return to the mating portion of said tubular container.

6. The invention as defined in claim wherein said flow means includes a convolute structure comprising a helical wire element fabricated of relatively small diametrical size wire.

7. The invention as defined in claim 5 wherein said first thermal substance includes a fluid which is unsolidified at ordinary temperatures, and further comprising a heat exchanger including a radiator having heat transferring 'fins affixed to a predetermined part thereof and a tubular coupling surface generally positioned concentrically in proximity to said predetermined part of said container second portion, and a second substance of proper thermal conductivity generally filling the space between said tubular coupling surface and said predetermined part of said container second portion, and wherein said tubular body has heat gathering fins affixed to a predetermined part thereof, and said heat input environment includes a generally solid medium and said heat output environment includes a generally fluid medium.

8. A separable heat pipe assembly comprising: a sheath including a tubular body, said sheath being part of a support structure, and at least partially exposed to a heat input environment which includes a generally permafrost medium;

a heat pipe element including a tubular container having a charge of working fluid therein, said heat pipe element being adapted to be installed in said sheath, and said tubular container comprising a first portion including a predetermined part which can be accommodated in said tubular body and mating therewith, and a second portion including a predetermined part adapted to be coupled to a heat exchanger at least partially exposed to a heat output environment which includes a generally atmospheric air medium; and

a first substance having a thermal conductivity greater than air generally filling the space between the mating portions of said tubular body and tubular container, said first thermal substance including a fluid which is unsolidified at ordinary temperatures, whereby heat picked up by said sheath from said heat input environment is conducted by said first thermal substance to the mating portion of said heat pipe element and transported by said working fluid in vaporized form to said predetermined part of said container second portion coupled to said heat exchanger for transfer to said heat output environment accompanied with condensation of said vaporized working fluid for return to the mating portion of said tubular container.

9. The invention as defined in claim 8 further comprising flow means for generally directing and spreading condensate flow back to said mating portion of said tubular container, said flow means including a convolute structure provided directly on a predetermined length of the interior longitudinal wall of said tubular container to spread and maintain the condensate flow thereover.

10. The invention as defined in claim 8 further comprising a heat exchanger including a radiator having heat transferring fins affixed to a predetermined part thereof and a tubular coupling surface generally positioned concentrically in proximity to said predetermined part of said container second portion, and a second substance of proper thermal conductivity generally filling the space between said tubular coupling surface and said predetermined part of said container second portion.

zg gg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION 3,823,769 Dated July 16, 197M Patent No.

John H. Anderson and Elmer D. Waters Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 12, line 19, the numeral "8," should read --lO- Signed and sealed this 19th day of November 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents 

1. A separable heat pipe assembly for installation in a permafrost environment comprising: a sheath including a tubular body, said sheath being at least partially exposed to a heat input environment, and said tubular body being closed at one end and open at the other end; a heat pipe element including a tubular container having a charge of working fluid therein, said tubular container comprising a first portion including a predetermined part which can be accommodated in said tubular body and mating therewith, and a second portion including a predetermined part adapted to be coupled to a heat exchanger at least partially exposed to a heat output environment, said predetermined part of said container first portion having an exterior shape complementary to the interior shape of said tubular body, and the mating portions of said tubular body and tubular container being closely spaced from each other; and a first substance having a thermal conductivity greater than air generally filling the space between the mating portions of said tubular body and tubular container, said first thermal substance including a fluid which is unsolidified at ordinary temperatures, whereby heat picked up by said sheath from said heat input environment is conducted by said first thermal substance to the mating portion of said heat pipe element and transported by said working fluid in vaporized form to said predetermined part of said container second portion coupled to said heat exchanger for transfer to said heat output environment accompanied with condensation of said vaporized working fluid for return to the mating portion of said tubular container.
 2. The invention as defined in claim 1 wherein the mating portions of said tubular body and tubular container are generally spaced in the order of about 0.015 inch from each other.
 3. The invention as defined in claim 1 wherein said fluid includes a liquid mixture of water and ethylene glycol.
 4. The invention as defined in claim 1 further comprising a heat exchanger including a radiator having a coupling surface positioned in proximity to said predetermined part of said container second portion, and a second substance of proper thermal conductivity generally filling the space between said coupling surface and said predetermined part of said container second portion.
 5. A separable heat pipe assembly for installation in a permafrost environment comprising: a sheath including a tubular body, said sheath being at least partially exposed to a heat input environment; a heat pipe element including a tubular container having a charge of working fluid therein, said tubular container comprising a first portion including a predetermined part which can be accommodated in said tubular body and mating therewith, and a second portion including a predetermined part adapted to be coupled to a heat exchanger at least partially exposed to a heat output environment; a first unsolidified at ordinary temperatures substance having a thermal conductivity greater than air generally filling the space between the mating portions of said tubular body and tubular container; and flow means for generally directing and spreading condensate flow back to said mating portion of said tubular container, said flow means including a convolute structure provided directly on a predetermined length of the interior longitudinal wall of said tubular container to spread and maintain the condensate flow thereover, whereby heat picked up by said sheath from said heat input environment is conducted by said first thermal substance to the mating portion of said heat pipe element and transported by said working fluid in vaporized form to said predetermined part of said container second portion coupled to said heat exchanger for transfer to said heat output environment accompanied with condensation of said vaporized working fluid for return to the mating portion of said tubular container.
 6. The invention as defiNed in claim 5 wherein said flow means includes a convolute structure comprising a helical wire element fabricated of relatively small diametrical size wire.
 7. The invention as defined in claim 5 wherein said first thermal substance includes a fluid which is unsolidified at ordinary temperatures, and further comprising a heat exchanger including a radiator having heat transferring fins affixed to a predetermined part thereof and a tubular coupling surface generally positioned concentrically in proximity to said predetermined part of said container second portion, and a second substance of proper thermal conductivity generally filling the space between said tubular coupling surface and said predetermined part of said container second portion, and wherein said tubular body has heat gathering fins affixed to a predetermined part thereof, and said heat input environment includes a generally solid medium and said heat output environment includes a generally fluid medium.
 8. A separable heat pipe assembly comprising: a sheath including a tubular body, said sheath being part of a support structure, and at least partially exposed to a heat input environment which includes a generally permafrost medium; a heat pipe element including a tubular container having a charge of working fluid therein, said heat pipe element being adapted to be installed in said sheath, and said tubular container comprising a first portion including a predetermined part which can be accommodated in said tubular body and mating therewith, and a second portion including a predetermined part adapted to be coupled to a heat exchanger at least partially exposed to a heat output environment which includes a generally atmospheric air medium; and a first substance having a thermal conductivity greater than air generally filling the space between the mating portions of said tubular body and tubular container, said first thermal substance including a fluid which is unsolidified at ordinary temperatures, whereby heat picked up by said sheath from said heat input environment is conducted by said first thermal substance to the mating portion of said heat pipe element and transported by said working fluid in vaporized form to said predetermined part of said container second portion coupled to said heat exchanger for transfer to said heat output environment accompanied with condensation of said vaporized working fluid for return to the mating portion of said tubular container.
 9. The invention as defined in claim 8 further comprising flow means for generally directing and spreading condensate flow back to said mating portion of said tubular container, said flow means including a convolute structure provided directly on a predetermined length of the interior longitudinal wall of said tubular container to spread and maintain the condensate flow thereover.
 10. The invention as defined in claim 8 further comprising a heat exchanger including a radiator having heat transferring fins affixed to a predetermined part thereof and a tubular coupling surface generally positioned concentrically in proximity to said predetermined part of said container second portion, and a second substance of proper thermal conductivity generally filling the space between said tubular coupling surface and said predetermined part of said container second portion. 